Petcare companies have for many years provided commercial petfoods to various markets around the world. Commercial petfood products are designed to be nutritious, but are also required to be highly palatable to ensure the animal consumes sufficient volume to receive its nutritional requirements, and to ensure the pet owner is satisfied that the product is ‘satisfying’ the animal's needs.
One of the aesthetic drawbacks of traditional commercial petfoods is that they have been perceived by pet owners as ‘artificial’, and by inference, not as healthy or satisfying for the animal. This perception may exist quite independently of the actual nutritional or sensory performance of the products.
Therefore, to enhance the owner's perception of these products, there has always been a need to provide a ‘meat-like’ texture in commercial petfoods, in order to provide ‘real food’ cues to the owner of the pet and to provide satisfying texture to the animal.
To provide the ‘muscle meat’ texture that is desirable, but on a cost-effective basis, commercial petfood manufacturers have developed various technologies to make manufactured meat analogues, or meat-like chunks. This is often done by utilizing the binding functionality of selected raw material to form an integral mass from comminuted meat and/or cereal slurries via various processes. The recent evolution of this technology is summarized as follows:
1970's
Lower-moisture extruded vegetable protein has been used as a ‘chunk’ in packaged foods. It has a ‘meaty’ internal texture, but does not have good palatability, particularly for felines. Also, the requirement for high levels of sulfur in the recipe is a drawback in relation to its undesirable impact on the product and packaging aesthetics.
Meat slurries were created from low-grade meat offals, cooked in gas ovens and cut into chunks. However, these chunks tended to be not as palatable as muscle meat and did not display a satisfactorily ‘meaty’ internal texture.
Lung lobes have been cut to resemble muscle meat. However the sorting and trimming required to obtain the lobes themselves, as well as the poor recovery of lung chunks through high-volume size reduction processes, and the further poor recovery of chunk size post canning, are significant drawbacks for this technique.
1980's
Meat analogue chunks manufactured from meat slurries were made resilient via the use of materials with binding properties such as cereal starch/konjac/alginate/pectin. However, many of these chunks lacked realistic texture, especially internally. Some of the binders also tended to be relatively expensive.
1990's
‘Steam-Set Meat’ (SSM) chunks formed from slurries cooked in steam ovens and cut into chunks, particularly utilizing the water binding ability of such materials as egg white, blood plasma, soy protein isolate, selected chicken pieces, cereal binders and gelling agents to provide resilience. The chunks themselves were not superior to the gas-oven chunks, however this technique was preferred to gas-oven cooking due to the elimination of fires and due to lower maintenance costs.
SSM chunks are also prone to degradation during mixing and filling operations, and lack a realistic ‘meaty’ internal texture. They also require a complex multi-stage manufacturing process, and depend on the binding ability of high cost ingredients such as blood plasma and wheat gluten and muscle meats for resilience.
2000's
Utilisation of higher-moisture extrusion techniques to create a Higher Moisture Extruded Chunk (HMEC) that is highly digestible and palatable, yet resilient during mixing and filling operations. One such operation is described in PCT Patent Application No. PCT/AU00/00475, in the name of Effem Foods Pty Ltd. The resultant product is capable of replicating the textured appearance of beef, lamb, chicken and fish. It will be understood by those skilled in the art that reference to ‘higher-moisture extrusion’ encompasses extrusion cooking of materials having an overall moisture content of greater than about 30% by mass.
However, one of the requirements of successful higher-moisture extrusion is that the proteinaceous feed stream is low in fat and ideally also low in water. The type of higher-moisture and/or high fat slurries traditionally used for meat-based chunks tends to be too low in viscosity for extrusion. Technically, this may be overcome by the addition of high-grade protein sources such as wheat gluten, soy protein and spray-dried egg white, as well as other high-cost, low-fat meat streams such as liver. However, these materials are too high in cost to be contemplated for the vast majority of commercial petfood products.
For a commercial pet food manufacturer to improve the utilization of the above described HMEC and SSM technologies in packaged pet foods, it is accordingly desirable to ameliorate some or all of the disadvantages of these technologies.
In parallel, the development of lower-moisture extruded commercial pet foods has driven a demand for:
tallow as a palatability and fat source to provide sufficient dietary energy in an otherwise mainly cereal-based product; and
Palatable, aqueous coatings that may be sprayed on to the extruded kibbles to improve their palatability.
It will be understood by those skilled in the art that reference to ‘lower-moisture extrusion’ encompasses extrusion cooking of materials having an overall moisture content of less than about 30% by mass. Similarly, ‘lower moisture foods’ are equivalent to food materials having a moisture content of less than about 30% by mass.
It will further be understood by those skilled in the art that reference to ‘higher-moisture extrusion’ encompasses extrusion cooking of materials having an overall moisture content of greater than about 30% by mass. Similarly, ‘higher moisture foods’ are equivalent to food materials having a moisture content of greater than about 30% by mass.
Tallow is typically obtained from commercial rendering plants, where mammal by-products not directed to the human or pet foods streams are processed. Recently, however, concerns have grown regarding the introduction of ‘specific risk materials’ (SRM's) into the mammalian food stream. These materials include spleen, brain, and spinal cord, and are associated with degenerative diseases such as Bovine Spongiform Encephalopathy (BSE). As these materials are often processed by renderers, there is a significant risk that these materials may be incorporated into commercial lower-moisture petfoods, with a potential long-term health risk for the animal. Therefore, it would be advantageous to develop an alternative, low-cost fat source that is free of BSE risk.
In parallel with the above issues, there is a desire to improve the profitability of commercial pet food operations by reducing the expense and complexity of the red meat, chicken and fish supply chain. A typical flow chart for the red meat supply stream to a commercial pet food manufacturer is shown in FIG. 1.
Typically, bovine, ovine and porcine materials are directed to one of three main streams at the abattoir: ‘human consumption’, ‘petfood only’ and ‘condemned’. The mixed organs of the petfood stream are directed to large bins.
At the collector, usually a separate plant to the abattoir and the petfood manufacturer, the petfood offal bins are sorted into their components such as lung, liver, hearts, kidneys and others with the remaining material stream called offcuts. Offcuts may include: muscle meat trims, tongue roots, trachea, gullets, weasands, liver, lung off-cuts, hearts, kidney, pig testes, pig skin and blooded lung lobe trims, among other things. Considerable expenses are incurred in refrigerated storage and transport of the mixed offal from abattoir to collector, manual sorting and trimming of various organs at the collector, and subsequent frozen storage and transport to the petfood manufacturer. Therefore, there would be considerable advantage in removing or reducing the petfood manufacturer's reliance on the collector. However, there are some obstacles to be overcome in doing this.
In the past, there were no chunk manufacturing technologies that could successfully utilize unsorted, or only partially sorted, red meat organs. Sorting allows the particular properties of particular organs to be specifically utilized in the pet foods products, both in chunks and in the ‘background’ of the petfoods, while allowing the diversion of troublesome ingredients such as offcuts away from the critical manufacturing processes and products. The typical distribution of these sorted materials in a commercial packaged petfood manufacturing process is illustrated in FIG. 2. It will be understood by those skilled in the art that reference to ‘packaged’ petfoods is also intended to encompass all packaging formats in which commercially sterilised, higher-moisture petfoods are packaged. These other packaging formats may include sealed aluminium trays and sealed pouches made from flexible films. The typical distribution of these sorted materials in a commercial lower-moisture packaged petfood manufacturing process is illustrated in FIG. 3.
The offcuts stream is extremely variable, particularly in fat level (typical range is 10%-40% but may vary outside these limits). This variability limits its use in chunk manufacture and canning processes due to the interference of the fat on the protein setting process, which in turn has an adverse effect on the product aesthetics. The “cookout” which occurs from this material during canning also tends to degrade the appearance of the product.
As described above for red meats, chicken and other poultry-based materials undergo multiple process, storage and transport stages in between slaughter and the petfood manufacturer. This significantly adds to the effective cost of these materials to the petfood manufacturer. The typical chicken material collection process is shown in FIG. 4.
These materials are received as either ‘Chicken Offals’—a stream of heads, feet, bones and viscera in varying ratios, and hence variable fat and moisture content, or as ‘Chicken Pieces’—chicken frames and other whole chicken components which, while they may vary in composition, are valuable due to the functionality of the protein contained therein. This functionality could potentially be used to reduce reliance on expensive functional protein isolates, such as egg white powder, blood plasma and soy protein isolate. However, inherent variations in fat and moisture tend to interfere with the functionality of the protein.
Therefore, it is desired to provide a method of more efficiently collecting and processing red meat and poultry offal, in order to facilitate the improved quality and cost-effectiveness of commercial petfood manufacture.